1. Field of the Invention
This invention is directed to apparatus for cutting out of a stream of bulk material, or precrushed coal, a sample and, in a series of steps, securing further fractions of the original sample, a final one of which is then analyzed for important characteristics.
2. Description of the Prior Art
In actual practice of the art of coal sampling it is observed that apparatus for performing that task has depended upon a tower structure which is designed to initially elevate a lot or quantity of coal to the upper reach of the tower and allow it to fall by gravity into sampling devices. The problem with these installations is that expensive structure is required and coal elevating means is used to move reject coal to a discharge conveyor. In addition, the structure is so complicated that field erection is required and that adds cost to the final installation.
Efforts have been made to reduce the size of coal sampler structures. An early coal sampling apparatus conveyed the coal to an elevated position for establishing a free falling stream from which samples could be extracted and processed using flow guiding mechanism and auxiliary conveyors. Such an arrangement is shown in Pletta et al U.S. Pat. No. 2,495,944 of Jan. 31, 1950. This was followed by sampler mechanism employing complicated sample collector motion that was circular for collecting a sample and linear to dump the sample at a location removed from the margin coal stream. Reference is made to Jordison U.S. Pat. No. 2,977,800 of Apr. 4, 1961. An effort to improve on Jordison is disclosed in Clewlow U.S. Pat. No. 3,875,803 of Apr. 8, 1975 where instead of moving the sampler in a linear direction to a dump position, the sampler merely swung to a set position after making a sample cut through a falling stream, and a discharge chute was moved up to collect the sample and direct it into a collection chute. A somewhat similar sampler for bulk material is shown in Jordison U.S. Pat. No. 3,541,862 of Nov. 24, 1970. In this latter apparatus the sampler moved in a fixed curved guide to cut a sample from a free falling stream and deliver it to a fixed position chute where the sample was released to a chute.
A somewhat similar approach to sampling bulk material is disclosed by Gundersen et al U.S. Pat. No. 4,326,425 of Apr. 27, 1982. In this arrangement, a sampler bucket must be rotated while being swung in a curved path so it will only cut a sample in one direction of its passage through the falling stream. The bucket is required to rotate after its arrival at a dump station so its sample can be spilled into a chute and directed to processing means.
The foregoing prior art sets forth disclosures of complicated arrangements of structure which greatly increases the cost and entails a system of controls for achieving the dumping of the sample after it has been collected. There is a more serious problem in the prior art and that is the sample collecting means is required to pass through the stream of material twice but only collecting or cutting out a sample on one pass which means that the stream is disturbed during the non-collecting pass and the material in the stream is scattered at that time.